Eosinophilic dermatosis of haematological malignancy

This report is about a 71-year-old woman with a background of chronic lymphocytic leukaemia (CLL) diagnosed in 2017, managed conservatively with active surveillance under haematology. Presented to dermatology 5 years ago with a non-resolving insect bite-like rash on her chest. Multiple biopsies were taken over the years due to the diagnostic challenge. The biopsies usually demonstrated perivascular inflammation, heavy eosinophilic infiltrate along with lymphocytes and histiocytes, without evidence of a frank vasculitis. Following multidisciplinary team discussion with clinical and pathological correlation, a diagnosis of eosinophilic dermatosis of haematological malignancy mimicking insect bites was made.